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United States Patent |
5,243,110
|
Castella Sola
,   et al.
|
September 7, 1993
|
Dehydrochlorination of 1,1-bis(R-phenyl)-2,2,2-trichloroethanes
Abstract
1,1-Bis(R-phenyl)-2,2,2-trichloroethanes are dehydrochlorinated in high
yields, e.g., into 1,1-bis(chlorophenyl)-2,2-dichloroethylenes, by
reacting same with an aqueous solution of an alkali metal hydroxide, in
liquid state in the presence of a phase transfer agent, e.g., a quaternary
ammonium compound, but in the absence of any reaction solvent.
Inventors:
|
Castella Sola; Jaume (Barcelona, ES);
Palencia Adrubau; Jaime (Barcelona, ES)
|
Assignee:
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Elf Atochem S.A. (Puteaux, FR)
|
Appl. No.:
|
901072 |
Filed:
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June 19, 1992 |
Foreign Application Priority Data
Current U.S. Class: |
570/204; 570/205 |
Intern'l Class: |
C07C 025/20; C07C 017/24 |
Field of Search: |
570/204,205
|
References Cited
U.S. Patent Documents
4337368 | Jun., 1982 | Pytlewski et al. | 570/204.
|
4960962 | Oct., 1990 | Brackenridge | 570/204.
|
Foreign Patent Documents |
0584119 | Oct., 1959 | CA | 570/204.
|
Primary Examiner: Lone; Werren B.
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis
Claims
What is claimed is:
1. A process for the dehydrochlorination of a
1,1-bis(R-phenyl)-2,2,2-trichloroethane, comprising reacting
1,1-bis(R-phenyl)-2,2,2-trichloroethane, wherein R is a hydrogen or
halogen atom, hydroxyl or nitro group, or alkyl or alkoxy radical, with an
aqueous solution of an alkali metal hydroxide in liquid state in the
presence of a phase transfer agent, but in the absence of any reaction
solvent.
2. The process as defined by claim 1, said phase transfer agent comprising
a quaternary ammonium compound.
3. The process as defined by claim 2, said phase transfer agent comprising
dimethyllaurylbenzylammonium chloride.
4. The process as defined by claim 1, comprising incrementally adding said
alkali metal hydroxide to the liquid medium of reaction.
5. The process as defined by claim 1, said alkali metal hydroxide
comprising sodium hydroxide.
6. The process as defined by claim 1,
1,1-bis(R-phenyl)-2,2,2-trichloroethane comprising a
1,1-bis(chlorophenyl)-2,2,2-trichloroethane.
7. A process for the dehydrochlorination of a
1,1-bis(R-phenyl)-2,2,2-trichloroethane, comprising reacting
1,1-bis(R-phenyl)-2,2,2-trichloroethane, wherein R is a hydrogen or
halogen atom, hydroxyl or nitro group, or alkyl or alkoxy radical, with an
aqueous solution of an alkali metal hydroxide in liquid state in the
presence of a phase transfer agent which permits contact between the
compound to be dehydrochlorinated and the alkali metal hydroxide, but in
the absence of any reaction solvent to obtain a dehydrochlorinated product
of said 1,1-bis(R-phenyl)-2,2,2-trichloroethane.
8. A process for the dehydrochlorination of a
1,1-bis(R-phenyl)-2,2,2-trichloroethane, comprising reacting
1,1-bis(R-phenyl)-2,2,2-trichloroethane, wherein R is a hydrogen or
halogen atom, hydroxyl or nitro group, or alkyl or alkoxy radical, with an
aqueous solution of an alkali metal hydroxide in liquid state in the
presence of a phase transfer agent comprising a quaternary ammonium
compound which permits contact between the compound to be
dehydrochlorinated and the alkali metal hydroxide, but in the absence of
any reaction solvent to obtain a dehydrochlorinated product of said
1,1-bis(R-phenyl)-2,2,2-trichloroethane.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improved process for
dehydrochlorinating 1,1-bis(R-phenyl)-2,2,2-trichloroethanes.
2. Description of the Prior Art
The 1,1-bis(R-phenyl)-2,2,2-trichloroethanes are known to this art. For
example, 1,1-bis(chlorophenyl)-2,2,2-trichloroethane (DDT) is an
intermediate compound in the synthesis of
1,1-bis(chlorophenyl)-2,2,2-trichloroethanol, commonly known as dicofol,
an acaricide applied to cotton crops and fruit trees.
DDT is dehydrochlorinated to 1,1-bis(chlorophenyl)-2,2-dichloroethylene
(DDE) which is then chlorinated to prepare
1,1-bis(chlorophenyl)-1,2,2,2-tetrachloroethane (chloroDDT), which in turn
is hydrolyzed to dicofol according to the reaction sequence:
##STR1##
Polish Patent PL-110,642 (Chemical Abstracts, Vol. 96: 122386 h (1982))
describes the dehydrochlorination of diphenyltrichloroethane (C.sub.6
H.sub.5).sub.2 CH--CCl.sub.3 to diphenyldichloroethylene (C.sub.6
H.sub.5).sub.2 C.dbd.CCl.sub.2, the process being carried out in benzene
with sodium hydroxide and methylbis(polyoxyethylene)stearylammonium
chloride.
Russian Patent SU-899,524 (Chemical Abstracts, Vol. 97: 55461 j (1982))
describes the dehydrochlorination of
1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (p--ClC.sub.6 H.sub.4).sub.2
CH--CCl.sub.3 with an alkali metal hydroxide, the process being carried
out in ethanol or isopropanol.
And Polish Patent PL-112,229 (Chemical Abstracts, Vol. 96: 162301 h (1982)
describes the dehydrochlorination of
bis(para-hydroxyphenyl)trichloroethane (4--HOC.sub.6 H.sub.4).sub.2
CH--CCl.sub.3 in methanol in the presence of a basic, quaternary ammonium
ion exchange resin.
The presence of a reaction solvent such as benzene, ethanol, isopropanol or
methanol presents difficulties in the event that a chlorination is to be
carried out downstream of the dehydrochlorination operation, because such
a solvent can itself be chlorinated.
If the product obtained via the dehydrochlorination is to be isolated, the
presence of solvent makes the separation more complex.
SUMMARY OF THE INVENTION
Accordingly, a major object of the present invention is the provision of an
improved process for the dehydrochlorination of
1,1-bis(R-phenyl)-2,2,2-trichloroethanes by means of an aqueous solution
of an alkali metal hydroxide, the reaction being carried out in the
absence of solvent but in the presence of a phase transfer agent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
More particularly according to the present invention, the radical R is one
or more hydrogen or halogen atoms, alkyl radicals, hydroxyl (OH) or
NO.sub.2 groups or alkoxy radicals. Methyl, ethyl, propyl and isopropyl
are exemplary alkyl radicals. Methoxy and ethoxy are exemplary alkoxy
radicals. A combination of different substituents may also be present on
the same phenyl nucleus, different substituents on each of the phenyl
nuclei, only one substituted phenyl nucleus, or any combination of these
substituents.
Although the process may be carried out over a wide pressure range, it is
conducted at sufficient pressure to maintain the
1,1-bis(R-phenyl)-2,2,2-trichloroethane and the aqueous alkali metal
hydroxide solution in the liquid state.
By "phase transfer agent" is intended a reagent which permits contact
between the compound to be dehydrochlorinated and the alkali metal
hydroxide. Numerous materials are known to this art which perform this
function. For example, the quaternary ammonium compounds are
representative, e.g., dimethyllaurylbenzylammonium chloride.
It is also within the scope of this invention to incrementally add the
alkali metal hydroxide solution a number of times over the course of the
reaction, or to supplement the alkali metal hydroxide content of the
reaction mixture by additions of anhydrous or highly concentrated alkali
metal hydroxide, such as flaked potassium hydroxide or sodium hydroxide.
This permits a reduction in the amount of alkali metal hydroxide used,
while maintaining the sodium chloride formed in solution. Upon completion
of the reaction, it suffices to separate off the organic phase containing
the compound to be dehydrochlorinated and the dehydrochlorinated compound
from the alkaline aqueous phase; this operation can be carried out simply
by phase separation.
In order to further illustrate the present invention and the advantages
thereof the following specific examples are given, it being understood
that same are intended only as illustrative and in nowise limitative.
EXAMPLE 1 (Comparative)
420 g of 1,1-bis(chlorophenyl)-2,2,2-trichloroethane were melted and 270 g
of 50% strength aqueous sodium hydroxide were introduced therein with
stirring and at a temperature of 100.degree.-105.degree. C. After 20 hours
of reaction, the mixture was diluted with 300 g of water. The organic
phase was separated off and washed twice with 100 g of water and 371.9 g
of a mixture of 1,1-bis(chlorophenyl)-2,2-dichloroethylene and
1,1-bis(chlorophenyl)-2,2,2-trichloroethane (15.5%) was obtained.
EXAMPLE 2 (Comparative)
60.6 g of 50% strength aqueous sodium hydroxide and two drops of an
antifoaming agent were added to a solution of 250 g of
1,1-bis(chlorophenyl)-2,2,2-trichloroethane in 250 g of isobutanol. The
mixture was heated until the isobutanol/water azeotrope distilled, while
being maintained at reflux for 1 hour. The water was separated off by
azeotropic distillation of the water/isobutanol, while adding isobutanol.
After separation of the water, the separated solid phase was filtered off
at room temperature and the isobutanol was distilled from the liquid
phase. 217.9 g of 1,1-bis(chlorophenyl)-2,2-dichloroethylene were obtained
(y=97.2%) with 0.18% of 1,1-bis(chlorophenyl)-2,2,2-trichloroethane.
EXAMPLE 3 (Comparative)
201.5 g of 28% strength aqueous sodium hydroxide and 2.0 g of
dimethyllaurylbenzylammonium chloride were added to a solution of 250 g of
1,1-bis(chlorophenyl)-2,2,2-trichloroethane in 100 g of monochlorobenzene
at 50.degree. C. The mixture was heated at reflux (90.degree. C.) for 20
hours. The organic phase was separated by phase separation and was washed
three times with 100 g of water. After distillation of the
monochlorobenzene, 219.3 g of 1,1-bis(chlorophenyl)-2,2-dichloroethylene
were obtained (y=97.8%) with 0.10% of
1,1-bis(chlorophenyl)-2,2,2-trichloroethane.
EXAMPLE 4
150 g of solid 1,1-bis(chlorophenyl)-2,2,2-trichloroethane were added to
248.8 g of a 27.2% strength aqueous sodium hydroxide solution maintained
at 93.degree. C. 1.4 g of dimethyllaurylbenzylammonium chloride were added
thereto. The temperature increased from 93.degree. to 103.degree. C. The
addition of solid 1,1-bis(chlorophenyl)-2,2,2-trichloroethane was
continued up to a total amount of 300 g. 1.1 g of
dimethyllaurylbenzylammonium chloride were added again and the temperature
was maintained between 100.degree. and 105.degree. C. for 14 hours, 30
min. The organic phase was separated off by phase separation and washed
three times with 100 g of a 1N solution of sulfuric acid and with water
(100 g). 263.7 g of 1,1-bis(chlorophenyl)-2,2-dichloroethylene were
obtained (y=98.0%) with 0.09% of
1,1-bis(chlorophenyl)-2,2,2-trichloroethane.
EXAMPLE 5
990 kg of solid 1,1-bis(chlorophenyl)-2,2,2-trichloroethane were charged
into the basic aqueous phase emanating from an upstream
dehydrochlorination operation. The charging period was 2 hours to avoid
the formation of solid masses inside the reactor. 5 kg of
dimethylbenzyllaurylammonium chloride were added, while intense stirring
was continued for 4 hours at 100.degree.. After 1 hour at rest, the
aqueous phase was separated off and 268 kg of 50% strength sodium
hydroxide were added and the dehydrochlorination was continued with
stirring at 100.degree. C. for 10 hours. After dilution with 560 kg of
water and 1 hour at rest, the organic phase was drawn off and the aqueous
phase was retained for the following operation. The organic phase was then
washed 3 times with 250 kg of a 1N solution of sulfuric acid and 879 kg of
1,1-bis(chlorophenyl)-2,2-dichloroethylene were obtained.
EXAMPLE 6
The procedure of Example 5 was repeated, except that technical
1,1-bis(chlorophenyl)-2,2,2-trichloroethane in the molten state at
92.degree. C. was used at the outset.
The 1,1-bis(chlorophenyl)-2,2,2-trichloroethane in the liquid state was
added to the basic aqueous phase from an upstream dehydrochlorination
operation and the dehydrochlorination was initiated with the addition of 5
kg of dimethylbenzyllaurylammonium chloride, while intense stirring was
maintained for 4 hours at 100.degree. C.
The procedure was then as is Example 5; the same results were obtained.
While the invention has been described in terms of various preferred
embodiments, the skilled artisan will appreciate that various
modifications, substitutions, omissions, and changes may be made without
departing from the spirit thereof. Accordingly, it is intended that the
scope of the present invention be limited solely by the scope of the
following claims, including equivalents thereof.
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